The HEI measures the intake of ten dietary components to provide a single score out of a possible 100 points. A diet with a score greater than 80 is considered "good," one with a score of 51-80 is considered "fair," and one with a score of less than 51 is considered "poor." Each component contributes equally to the overall score.

In the mid-1970s, the United States government began to focus on national health issues, particularly disease prevention and health promotion. The first document to focus on the nation's health was the Report of the President's Committee on Health Education (1973).

The heart, which is about the size of a human fist, is the body's largest, strongest, and most important muscle. The heart continuously pumps blood through the body, helps regulate and prolong health, and controls the flow (circulation) of blood to the lungs, organs, muscles, and tissues in the body.

The United States Census Bureau defines Hispanics as those who indicate their origin to be Mexican, Puerto Rican, Cuban, Central or South American (e.g., Dominican, Nicaraguan, Colombian) or other Hispanic origin. This designation is made independently of racial classification.

HIV (human immunodeficiency virus) was identified in 1983 by the French scientist Luc Montagier and his staff at the Pasteur Institute in Paris. Ever since that discovery, scientists have been searching for ways to treat those infected with HIV, and to produce a vaccine to prevent its spread.

Hyperglycemia, or high blood sugar, is the result of either too little insulin or of the body's inefficient use of insulin. Indicators of hyperglycemia include frequent urination, thirst, high levels of sugar in the urine, and high blood sugar.

Blood pressure is the force with which blood pushes against the artery walls as it travels through the body. Like air in a balloon, blood fills arteries to a certain capacity—and just as too much air pressure can cause damage to a balloon, too much blood pressure can harm healthy arteries.

Hypoglycemia, or abnormally low blood sugar, is caused by the impaired response (or failure) of the liver to release glucose as blood sugar levels decrease. The imbalance in the rate of glucose released from the liver and its use by other body tissues can result in the following hypoglycemic symptoms: hunger, nervousness, dizziness, confusion, sleepiness, difficulty speaking, feeling anxious or weak, irritability, sweating, loss of consciousness, and increased blood pressure.

Food-borne illness, often called food poisoning, is caused by pathogens or certain chemicals present in ingested food. Bacteria, viruses, molds, worms, and protozoa that cause disease are all pathogens, though there are also harmless and beneficial bacteria that are used to make yogurt and cheese.

The immune system is made up of cells, tissues, organs, and processes that identify a substance as abnormal or foreign and prevent it from harming the body. Primary defenses include the white blood cells, but skin, mucosa, normal bacteria, enzymes, and proteins also provide protection.

Inborn errors of metabolism are inherited disorders in which the body cannot metabolize the components of food (carbohydrates, proteins, and
The Guthrie test, given to newborns, helps doctors diagnose some inborn errors of metabolism before they cause permanent damage. The test requires a small sample of blood, usually taken from the heel.

The infant mortality rate is the number of infant deaths (during the first twelve months of life) per 1,000 live births. Before birth, a fetus faces major health risks from undernutrition during pregnancy, particularly from inadequate, absent, or delayed prenatal care.

The first year of life is a period of very rapid growth. An infant's birth weight doubles after about five months and triples by the first birthday, by which time the infant's length increases by half.

Insulin is a hormone produced by specialized cells in the pancreas. Secreted into the bloodstream at each meal, insulin helps the body use and store glucose (sugar) produced during the digestion of food.

Irradiation, or "electronic pasteurization," exposes food to a radiant source of energy, such as gamma rays or electron beams, for a brief period of time. Irradiation is a "cold" process that produces little heat, so food can remain packaged throughout the process—and until opened by the consumer.